Cita APA (7th ed.)

Freedman, P. (1949). The principles of scientific research. Macdonald.

Cita Chicago (17th ed.)

Freedman, Paul. The Principles of Scientific Research. Lond.: Macdonald, 1949.

Cita MLA (8th ed.)

Freedman, Paul. The Principles of Scientific Research. Macdonald, 1949.